2 * Atheros AR933X SoC built-in UART driver
4 * Copyright (C) 2011 Gabor Juhos <juhosg@openwrt.org>
6 * Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
8 * This program is free software; you can redistribute it and/or modify it
9 * under the terms of the GNU General Public License version 2 as published
10 * by the Free Software Foundation.
13 #include <linux/module.h>
14 #include <linux/ioport.h>
15 #include <linux/init.h>
16 #include <linux/console.h>
17 #include <linux/sysrq.h>
18 #include <linux/delay.h>
19 #include <linux/platform_device.h>
21 #include <linux/of_platform.h>
22 #include <linux/tty.h>
23 #include <linux/tty_flip.h>
24 #include <linux/serial_core.h>
25 #include <linux/serial.h>
26 #include <linux/slab.h>
28 #include <linux/irq.h>
29 #include <linux/clk.h>
31 #include <asm/div64.h>
33 #include <asm/mach-ath79/ar933x_uart.h>
35 #define DRIVER_NAME "ar933x-uart"
37 #define AR933X_UART_MAX_SCALE 0xff
38 #define AR933X_UART_MAX_STEP 0xffff
40 #define AR933X_UART_MIN_BAUD 300
41 #define AR933X_UART_MAX_BAUD 3000000
43 #define AR933X_DUMMY_STATUS_RD 0x01
45 static struct uart_driver ar933x_uart_driver;
47 struct ar933x_uart_port {
48 struct uart_port port;
49 unsigned int ier; /* shadow Interrupt Enable Register */
50 unsigned int min_baud;
51 unsigned int max_baud;
55 static inline bool ar933x_uart_console_enabled(void)
57 return config_enabled(CONFIG_SERIAL_AR933X_CONSOLE);
60 static inline unsigned int ar933x_uart_read(struct ar933x_uart_port *up,
63 return readl(up->port.membase + offset);
66 static inline void ar933x_uart_write(struct ar933x_uart_port *up,
67 int offset, unsigned int value)
69 writel(value, up->port.membase + offset);
72 static inline void ar933x_uart_rmw(struct ar933x_uart_port *up,
79 t = ar933x_uart_read(up, offset);
82 ar933x_uart_write(up, offset, t);
85 static inline void ar933x_uart_rmw_set(struct ar933x_uart_port *up,
89 ar933x_uart_rmw(up, offset, 0, val);
92 static inline void ar933x_uart_rmw_clear(struct ar933x_uart_port *up,
96 ar933x_uart_rmw(up, offset, val, 0);
99 static inline void ar933x_uart_start_tx_interrupt(struct ar933x_uart_port *up)
101 up->ier |= AR933X_UART_INT_TX_EMPTY;
102 ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
105 static inline void ar933x_uart_stop_tx_interrupt(struct ar933x_uart_port *up)
107 up->ier &= ~AR933X_UART_INT_TX_EMPTY;
108 ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
111 static inline void ar933x_uart_putc(struct ar933x_uart_port *up, int ch)
115 rdata = ch & AR933X_UART_DATA_TX_RX_MASK;
116 rdata |= AR933X_UART_DATA_TX_CSR;
117 ar933x_uart_write(up, AR933X_UART_DATA_REG, rdata);
120 static unsigned int ar933x_uart_tx_empty(struct uart_port *port)
122 struct ar933x_uart_port *up =
123 container_of(port, struct ar933x_uart_port, port);
127 spin_lock_irqsave(&up->port.lock, flags);
128 rdata = ar933x_uart_read(up, AR933X_UART_DATA_REG);
129 spin_unlock_irqrestore(&up->port.lock, flags);
131 return (rdata & AR933X_UART_DATA_TX_CSR) ? 0 : TIOCSER_TEMT;
134 static unsigned int ar933x_uart_get_mctrl(struct uart_port *port)
139 static void ar933x_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
143 static void ar933x_uart_start_tx(struct uart_port *port)
145 struct ar933x_uart_port *up =
146 container_of(port, struct ar933x_uart_port, port);
148 ar933x_uart_start_tx_interrupt(up);
151 static void ar933x_uart_stop_tx(struct uart_port *port)
153 struct ar933x_uart_port *up =
154 container_of(port, struct ar933x_uart_port, port);
156 ar933x_uart_stop_tx_interrupt(up);
159 static void ar933x_uart_stop_rx(struct uart_port *port)
161 struct ar933x_uart_port *up =
162 container_of(port, struct ar933x_uart_port, port);
164 up->ier &= ~AR933X_UART_INT_RX_VALID;
165 ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
168 static void ar933x_uart_break_ctl(struct uart_port *port, int break_state)
170 struct ar933x_uart_port *up =
171 container_of(port, struct ar933x_uart_port, port);
174 spin_lock_irqsave(&up->port.lock, flags);
175 if (break_state == -1)
176 ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
177 AR933X_UART_CS_TX_BREAK);
179 ar933x_uart_rmw_clear(up, AR933X_UART_CS_REG,
180 AR933X_UART_CS_TX_BREAK);
181 spin_unlock_irqrestore(&up->port.lock, flags);
185 * baudrate = (clk / (scale + 1)) * (step * (1 / 2^17))
187 static unsigned long ar933x_uart_get_baud(unsigned int clk,
194 div = (2 << 16) * (scale + 1);
203 static void ar933x_uart_get_scale_step(unsigned int clk,
215 for (tscale = 0; tscale < AR933X_UART_MAX_SCALE; tscale++) {
219 tstep = baud * (tscale + 1);
223 if (tstep > AR933X_UART_MAX_STEP)
226 diff = abs(ar933x_uart_get_baud(clk, tscale, tstep) - baud);
227 if (diff < min_diff) {
235 static void ar933x_uart_set_termios(struct uart_port *port,
236 struct ktermios *new,
237 struct ktermios *old)
239 struct ar933x_uart_port *up =
240 container_of(port, struct ar933x_uart_port, port);
243 unsigned int baud, scale, step;
245 /* Only CS8 is supported */
246 new->c_cflag &= ~CSIZE;
249 /* Only one stop bit is supported */
250 new->c_cflag &= ~CSTOPB;
253 if (new->c_cflag & PARENB) {
254 if (!(new->c_cflag & PARODD))
255 cs |= AR933X_UART_CS_PARITY_EVEN;
257 cs |= AR933X_UART_CS_PARITY_ODD;
259 cs |= AR933X_UART_CS_PARITY_NONE;
262 /* Mark/space parity is not supported */
263 new->c_cflag &= ~CMSPAR;
265 baud = uart_get_baud_rate(port, new, old, up->min_baud, up->max_baud);
266 ar933x_uart_get_scale_step(port->uartclk, baud, &scale, &step);
269 * Ok, we're now changing the port state. Do it with
270 * interrupts disabled.
272 spin_lock_irqsave(&up->port.lock, flags);
274 /* disable the UART */
275 ar933x_uart_rmw_clear(up, AR933X_UART_CS_REG,
276 AR933X_UART_CS_IF_MODE_M << AR933X_UART_CS_IF_MODE_S);
278 /* Update the per-port timeout. */
279 uart_update_timeout(port, new->c_cflag, baud);
281 up->port.ignore_status_mask = 0;
283 /* ignore all characters if CREAD is not set */
284 if ((new->c_cflag & CREAD) == 0)
285 up->port.ignore_status_mask |= AR933X_DUMMY_STATUS_RD;
287 ar933x_uart_write(up, AR933X_UART_CLOCK_REG,
288 scale << AR933X_UART_CLOCK_SCALE_S | step);
290 /* setup configuration register */
291 ar933x_uart_rmw(up, AR933X_UART_CS_REG, AR933X_UART_CS_PARITY_M, cs);
293 /* enable host interrupt */
294 ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
295 AR933X_UART_CS_HOST_INT_EN);
297 /* enable RX and TX ready overide */
298 ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
299 AR933X_UART_CS_TX_READY_ORIDE | AR933X_UART_CS_RX_READY_ORIDE);
301 /* reenable the UART */
302 ar933x_uart_rmw(up, AR933X_UART_CS_REG,
303 AR933X_UART_CS_IF_MODE_M << AR933X_UART_CS_IF_MODE_S,
304 AR933X_UART_CS_IF_MODE_DCE << AR933X_UART_CS_IF_MODE_S);
306 spin_unlock_irqrestore(&up->port.lock, flags);
308 if (tty_termios_baud_rate(new))
309 tty_termios_encode_baud_rate(new, baud, baud);
312 static void ar933x_uart_rx_chars(struct ar933x_uart_port *up)
314 struct tty_port *port = &up->port.state->port;
321 rdata = ar933x_uart_read(up, AR933X_UART_DATA_REG);
322 if ((rdata & AR933X_UART_DATA_RX_CSR) == 0)
325 /* remove the character from the FIFO */
326 ar933x_uart_write(up, AR933X_UART_DATA_REG,
327 AR933X_UART_DATA_RX_CSR);
329 up->port.icount.rx++;
330 ch = rdata & AR933X_UART_DATA_TX_RX_MASK;
332 if (uart_handle_sysrq_char(&up->port, ch))
335 if ((up->port.ignore_status_mask & AR933X_DUMMY_STATUS_RD) == 0)
336 tty_insert_flip_char(port, ch, TTY_NORMAL);
337 } while (max_count-- > 0);
339 spin_unlock(&up->port.lock);
340 tty_flip_buffer_push(port);
341 spin_lock(&up->port.lock);
344 static void ar933x_uart_tx_chars(struct ar933x_uart_port *up)
346 struct circ_buf *xmit = &up->port.state->xmit;
349 if (uart_tx_stopped(&up->port))
352 count = up->port.fifosize;
356 rdata = ar933x_uart_read(up, AR933X_UART_DATA_REG);
357 if ((rdata & AR933X_UART_DATA_TX_CSR) == 0)
360 if (up->port.x_char) {
361 ar933x_uart_putc(up, up->port.x_char);
362 up->port.icount.tx++;
367 if (uart_circ_empty(xmit))
370 ar933x_uart_putc(up, xmit->buf[xmit->tail]);
372 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
373 up->port.icount.tx++;
374 } while (--count > 0);
376 if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
377 uart_write_wakeup(&up->port);
379 if (!uart_circ_empty(xmit))
380 ar933x_uart_start_tx_interrupt(up);
383 static irqreturn_t ar933x_uart_interrupt(int irq, void *dev_id)
385 struct ar933x_uart_port *up = dev_id;
388 status = ar933x_uart_read(up, AR933X_UART_CS_REG);
389 if ((status & AR933X_UART_CS_HOST_INT) == 0)
392 spin_lock(&up->port.lock);
394 status = ar933x_uart_read(up, AR933X_UART_INT_REG);
395 status &= ar933x_uart_read(up, AR933X_UART_INT_EN_REG);
397 if (status & AR933X_UART_INT_RX_VALID) {
398 ar933x_uart_write(up, AR933X_UART_INT_REG,
399 AR933X_UART_INT_RX_VALID);
400 ar933x_uart_rx_chars(up);
403 if (status & AR933X_UART_INT_TX_EMPTY) {
404 ar933x_uart_write(up, AR933X_UART_INT_REG,
405 AR933X_UART_INT_TX_EMPTY);
406 ar933x_uart_stop_tx_interrupt(up);
407 ar933x_uart_tx_chars(up);
410 spin_unlock(&up->port.lock);
415 static int ar933x_uart_startup(struct uart_port *port)
417 struct ar933x_uart_port *up =
418 container_of(port, struct ar933x_uart_port, port);
422 ret = request_irq(up->port.irq, ar933x_uart_interrupt,
423 up->port.irqflags, dev_name(up->port.dev), up);
427 spin_lock_irqsave(&up->port.lock, flags);
429 /* Enable HOST interrupts */
430 ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
431 AR933X_UART_CS_HOST_INT_EN);
433 /* enable RX and TX ready overide */
434 ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
435 AR933X_UART_CS_TX_READY_ORIDE | AR933X_UART_CS_RX_READY_ORIDE);
437 /* Enable RX interrupts */
438 up->ier = AR933X_UART_INT_RX_VALID;
439 ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
441 spin_unlock_irqrestore(&up->port.lock, flags);
446 static void ar933x_uart_shutdown(struct uart_port *port)
448 struct ar933x_uart_port *up =
449 container_of(port, struct ar933x_uart_port, port);
451 /* Disable all interrupts */
453 ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
455 /* Disable break condition */
456 ar933x_uart_rmw_clear(up, AR933X_UART_CS_REG,
457 AR933X_UART_CS_TX_BREAK);
459 free_irq(up->port.irq, up);
462 static const char *ar933x_uart_type(struct uart_port *port)
464 return (port->type == PORT_AR933X) ? "AR933X UART" : NULL;
467 static void ar933x_uart_release_port(struct uart_port *port)
469 /* Nothing to release ... */
472 static int ar933x_uart_request_port(struct uart_port *port)
474 /* UARTs always present */
478 static void ar933x_uart_config_port(struct uart_port *port, int flags)
480 if (flags & UART_CONFIG_TYPE)
481 port->type = PORT_AR933X;
484 static int ar933x_uart_verify_port(struct uart_port *port,
485 struct serial_struct *ser)
487 struct ar933x_uart_port *up =
488 container_of(port, struct ar933x_uart_port, port);
490 if (ser->type != PORT_UNKNOWN &&
491 ser->type != PORT_AR933X)
494 if (ser->irq < 0 || ser->irq >= NR_IRQS)
497 if (ser->baud_base < up->min_baud ||
498 ser->baud_base > up->max_baud)
504 static struct uart_ops ar933x_uart_ops = {
505 .tx_empty = ar933x_uart_tx_empty,
506 .set_mctrl = ar933x_uart_set_mctrl,
507 .get_mctrl = ar933x_uart_get_mctrl,
508 .stop_tx = ar933x_uart_stop_tx,
509 .start_tx = ar933x_uart_start_tx,
510 .stop_rx = ar933x_uart_stop_rx,
511 .break_ctl = ar933x_uart_break_ctl,
512 .startup = ar933x_uart_startup,
513 .shutdown = ar933x_uart_shutdown,
514 .set_termios = ar933x_uart_set_termios,
515 .type = ar933x_uart_type,
516 .release_port = ar933x_uart_release_port,
517 .request_port = ar933x_uart_request_port,
518 .config_port = ar933x_uart_config_port,
519 .verify_port = ar933x_uart_verify_port,
522 static struct ar933x_uart_port *
523 ar933x_console_ports[CONFIG_SERIAL_AR933X_NR_UARTS];
525 static void ar933x_uart_wait_xmitr(struct ar933x_uart_port *up)
528 unsigned int timeout = 60000;
530 /* Wait up to 60ms for the character(s) to be sent. */
532 status = ar933x_uart_read(up, AR933X_UART_DATA_REG);
536 } while ((status & AR933X_UART_DATA_TX_CSR) == 0);
539 static void ar933x_uart_console_putchar(struct uart_port *port, int ch)
541 struct ar933x_uart_port *up =
542 container_of(port, struct ar933x_uart_port, port);
544 ar933x_uart_wait_xmitr(up);
545 ar933x_uart_putc(up, ch);
548 static void ar933x_uart_console_write(struct console *co, const char *s,
551 struct ar933x_uart_port *up = ar933x_console_ports[co->index];
556 local_irq_save(flags);
560 else if (oops_in_progress)
561 locked = spin_trylock(&up->port.lock);
563 spin_lock(&up->port.lock);
566 * First save the IER then disable the interrupts
568 int_en = ar933x_uart_read(up, AR933X_UART_INT_EN_REG);
569 ar933x_uart_write(up, AR933X_UART_INT_EN_REG, 0);
571 uart_console_write(&up->port, s, count, ar933x_uart_console_putchar);
574 * Finally, wait for transmitter to become empty
575 * and restore the IER
577 ar933x_uart_wait_xmitr(up);
578 ar933x_uart_write(up, AR933X_UART_INT_EN_REG, int_en);
580 ar933x_uart_write(up, AR933X_UART_INT_REG, AR933X_UART_INT_ALLINTS);
583 spin_unlock(&up->port.lock);
585 local_irq_restore(flags);
588 static int ar933x_uart_console_setup(struct console *co, char *options)
590 struct ar933x_uart_port *up;
596 if (co->index < 0 || co->index >= CONFIG_SERIAL_AR933X_NR_UARTS)
599 up = ar933x_console_ports[co->index];
604 uart_parse_options(options, &baud, &parity, &bits, &flow);
606 return uart_set_options(&up->port, co, baud, parity, bits, flow);
609 static struct console ar933x_uart_console = {
611 .write = ar933x_uart_console_write,
612 .device = uart_console_device,
613 .setup = ar933x_uart_console_setup,
614 .flags = CON_PRINTBUFFER,
616 .data = &ar933x_uart_driver,
619 static void ar933x_uart_add_console_port(struct ar933x_uart_port *up)
621 if (!ar933x_uart_console_enabled())
624 ar933x_console_ports[up->port.line] = up;
627 static struct uart_driver ar933x_uart_driver = {
628 .owner = THIS_MODULE,
629 .driver_name = DRIVER_NAME,
630 .dev_name = "ttyATH",
631 .nr = CONFIG_SERIAL_AR933X_NR_UARTS,
632 .cons = NULL, /* filled in runtime */
635 static int ar933x_uart_probe(struct platform_device *pdev)
637 struct ar933x_uart_port *up;
638 struct uart_port *port;
639 struct resource *mem_res;
640 struct resource *irq_res;
641 struct device_node *np;
646 np = pdev->dev.of_node;
647 if (config_enabled(CONFIG_OF) && np) {
648 id = of_alias_get_id(np, "serial");
650 dev_err(&pdev->dev, "unable to get alias id, err=%d\n",
660 if (id >= CONFIG_SERIAL_AR933X_NR_UARTS)
663 irq_res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
665 dev_err(&pdev->dev, "no IRQ resource\n");
669 up = devm_kzalloc(&pdev->dev, sizeof(struct ar933x_uart_port),
674 up->clk = devm_clk_get(&pdev->dev, "uart");
675 if (IS_ERR(up->clk)) {
676 dev_err(&pdev->dev, "unable to get UART clock\n");
677 return PTR_ERR(up->clk);
682 mem_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
683 port->membase = devm_ioremap_resource(&pdev->dev, mem_res);
684 if (IS_ERR(port->membase))
685 return PTR_ERR(port->membase);
687 ret = clk_prepare_enable(up->clk);
691 port->uartclk = clk_get_rate(up->clk);
692 if (!port->uartclk) {
694 goto err_disable_clk;
697 port->mapbase = mem_res->start;
699 port->irq = irq_res->start;
700 port->dev = &pdev->dev;
701 port->type = PORT_AR933X;
702 port->iotype = UPIO_MEM32;
705 port->fifosize = AR933X_UART_FIFO_SIZE;
706 port->ops = &ar933x_uart_ops;
708 baud = ar933x_uart_get_baud(port->uartclk, AR933X_UART_MAX_SCALE, 1);
709 up->min_baud = max_t(unsigned int, baud, AR933X_UART_MIN_BAUD);
711 baud = ar933x_uart_get_baud(port->uartclk, 0, AR933X_UART_MAX_STEP);
712 up->max_baud = min_t(unsigned int, baud, AR933X_UART_MAX_BAUD);
714 ar933x_uart_add_console_port(up);
716 ret = uart_add_one_port(&ar933x_uart_driver, &up->port);
718 goto err_disable_clk;
720 platform_set_drvdata(pdev, up);
724 clk_disable_unprepare(up->clk);
728 static int ar933x_uart_remove(struct platform_device *pdev)
730 struct ar933x_uart_port *up;
732 up = platform_get_drvdata(pdev);
735 uart_remove_one_port(&ar933x_uart_driver, &up->port);
736 clk_disable_unprepare(up->clk);
743 static const struct of_device_id ar933x_uart_of_ids[] = {
744 { .compatible = "qca,ar9330-uart" },
747 MODULE_DEVICE_TABLE(of, ar933x_uart_of_ids);
750 static struct platform_driver ar933x_uart_platform_driver = {
751 .probe = ar933x_uart_probe,
752 .remove = ar933x_uart_remove,
755 .of_match_table = of_match_ptr(ar933x_uart_of_ids),
759 static int __init ar933x_uart_init(void)
763 if (ar933x_uart_console_enabled())
764 ar933x_uart_driver.cons = &ar933x_uart_console;
766 ret = uart_register_driver(&ar933x_uart_driver);
770 ret = platform_driver_register(&ar933x_uart_platform_driver);
772 goto err_unregister_uart_driver;
776 err_unregister_uart_driver:
777 uart_unregister_driver(&ar933x_uart_driver);
782 static void __exit ar933x_uart_exit(void)
784 platform_driver_unregister(&ar933x_uart_platform_driver);
785 uart_unregister_driver(&ar933x_uart_driver);
788 module_init(ar933x_uart_init);
789 module_exit(ar933x_uart_exit);
791 MODULE_DESCRIPTION("Atheros AR933X UART driver");
792 MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
793 MODULE_LICENSE("GPL v2");
794 MODULE_ALIAS("platform:" DRIVER_NAME);